1. Field of the Invention
This invention relates generally to telecommunication, and more particularly to high density perceptual evaluation of sound quality.
2. Description of the Related Art
Today, modern telecommunications systems often perform complex operations when transmitting signals through the telecommunications network. These operations generally have non-linear effects on the signal inputs. As a result, it is often not possible to model the effects of the network by simulating the additive affect of each component of the network. In particular, the affect of the network on speech is not easily derivable from studying the network's affect on a simple test signal such as a sine wave.
Hence, voice communication signals generally are tested using voice generation and analyzing equipment in the form of a telecommunication testing system. FIG. 1 is a block diagram showing an exemplary prior art telecommunication testing configuration 100. As shown in FIG. 1, the telecommunication testing configuration 100 includes a system under test (SUT) 102, such as a telecommunication system, in communication with a test system 104. One technique for testing the SUT 102 for voice quality of service (QoS) is call generation.
Call Generation is a testing mode in which the test system 104 creates telephone traffic by executing compiled call sequences (scripts). Typically, the test system 104 provides a maximal load on the SUT 102 to test the SUT 102. In particular, the test system 104 places voice data 108 on the input channels of the SUT 102 and receives degraded output data 110 from the SUT 102 in real time. Once received, the degraded output data 110 is tested using a perceptual evaluation of sound quality (PESQ) unit 106, as illustrated in FIG. 2.
FIG. 2 is a block diagram showing a conventional PESQ unit 106. The PESQ unit 106 receives degraded output data 110 from the SUT using a plurality of input channels. PESQ is calculated for each channel, not for a channels set, as it may be understood from the description. Once received, the PESQ unit 106 compares the degraded output data 110 to reference data to determine the perceptual evaluation of sound quality of the degraded output data 110. This quality is represented by a number referred to as a PESQ result 200. Generally, the PESQ result 200 is a number having a value between −0.5 and 4.5, which indicates the signal quality of the data returned from the SUT. Typically, a PESQ result value of 4.0-4.5 indicates high signal quality, while a PESQ result value bellow 2.0 indicates low signal quality.
In operation, the PESQ unit 106 should calculate the PESQ result prior to the end of a subsequent data frame, as illustrated next with reference to FIGS. 3A-3C. FIG. 3A illustrates conventional exemplary frame data 300. Generally, degraded data output from the SUT is divided into frames 300 of voice data, for example, 8-second frames of voice data. For example, FIG. 3A illustrates voice data divided into three 8-second frames 300, the first frame F1, followed by the second frame F2 and the third frame F3.
In operation, the PESQ unit processes each frame F1-F3 of the frame data 300 to determine the PESQ result for the particular frame. However, as mentioned above, each frame F1-F3 should be fully processed before the end of the subsequent frame, as illustrated in FIG. 3B. FIG. 3B illustrates a frame processing sequencing during proper signal quality evaluation. As shown in FIG. 3B, processing is started on the first frame F1 at time t0 and completed at time t1. Similarly, processing is started on the second frame F2 at time t1 and completed at time t2, and processing is started on the third frame F3 at time t2 and completed at time t3.
Thus, for proper signal quality evaluation, frame F1 should be processed prior to the end of frame F2. That is, the PESQ result for frame F1 should be calculated prior to time t2, as shown by the PESQ F1 result 302a. Similarly, the PESQ result for frame F2 should be calculated prior to time t3, as shown by the PESQ F2 result 302b. In this manner, the test system can process the voice data in real-time. However, if this cannot be maintained, problems can occur during voice data processing, as illustrated in FIG. 3C.
FIG. 3C illustrates an improper frame processing sequencing during delayed signal quality evaluation. As above, processing is started on the first frame F1 at time t0 and completed at time t1. Similarly, processing is started on the second frame F2 at time t1 and completed at time t2, and processing is started on the third frame F3 at time t2 and completed at time t3. However, in the example of FIG. 3C, the PESQ F1 result 302a for the first frame F1 is not calculated until after the second frame F2 has been processed. That is, the PESQ F1 result 302a for the first frame F1 is not calculated until after time t2. As a result, the test system will be unable to process the voice data in real-time and will experience problems because the voice data is entering the PESQ unit faster than the output of the unit is being generated. For example, if the PESQ result is not calculated before the subsequent frame is processed the PESQ unit will not evaluate some of incoming frames.
Process delays, such as that illustrated in FIG. 3C, can result from attempting to process too many voice data channels simultaneously. Thus, the speed of the test system defines the number of data channels the system can process simultaneously. For example, faster test systems can process more channels than slower test systems. Unfortunately, the prior art PESQ unit 106 is computationally slow, and as a result, prior art test systems are severely limited on the number of data channels that can be processed. Moreover, prior art PESQ units generally utilize floating point calculations, which can be exceedingly slow on PESQ DSPs that do not have co-processors to assist in floating point calculations.
In view of the foregoing, there is a need for systems and methods for high density telecommunication testing. The systems and methods should be capable of performing quality of service (QoS) testing on the SUT, and further, should support an increased number of simultaneous data channels without distorting the performance of the SUT.